What is the most important thing to do after knee surgery?
Figure out a way to work therapy into your daily routine otherwise, you'll be sorry. The therapy is absolutely essential to reduce the amount of scar tissue that will form. So what I do is put on my workout clothes, walk my child to school, workout while watching ZDTV, ice while eating breakfast/reading the paper. Net, net, it isn't much different than what I'd do anyway.

When can I stop using a knee brace?
When your muscles are as strong as they were before the accident. So don't do any new activity (like skiing again) without a brace to ensure your muscles are up to it. When your bad knee is as good as your good knee, you can lose the brace.

Why do I have reduced range of motion after the surgery?
Could be due to the graft placement or to scar tissue.

Can I get rid of scar tissue through physical therapy?
No, not after it is set in stone (xxx months after surgery). Another operation can remove it.

What exercises are the most important to do after surgery?
Straight leg raises, both with your foot at 12 o'clock, as well as pointed outward about 35 degrees. Bicycling is one of the best exercises in general. In the pool is even better.